Device for transcuticular application of active substance to plants

ABSTRACT

A device for the transcuticular administration of active substances to plants, and a method of using the same to treat plants with fungicidal, herbicidal, insecticidal and/or acaricidal substances.

This is a continuation of application Ser. No. 07/936,006 filed Aug. 27,1992, now abandoned, which is a divisional application of applicationSer. No. 07/844,866 filed Mar. 2, 1992, now U.S. Pat. No. 5,201,925,which in turn a continuation of application Ser. No. 07/727,362 filedJul. 9, 1991, now abandoned, which is in turn a continuation ofapplication Ser. No. 07/601,401 filed Oct. 23, 1990, now abandoned,which in turn a continuation of application Ser. No. 07/453,176 filedDec. 26, 1989, now abandoned, which is in turn a continuation ofapplication Ser. No. 07/074,277 filed Jul. 16, 1987, abandoned.

FIELD OF INVENTION

This invention relates to a device for transcuticular application ofmetered quantities of an active substance to plants, and to processesfor the preparation of such a device.

BACKGROUND OF THE INVENTION

In the field of plant protection, it is known to apply active substancesto the plants by spraying or dusting compositions which contain theactive substance onto the plants. The active substance acts either bydirect contact or systemically, that is, it is absorbed by the plantthrough the cuticles of the leaves.

The methods heretofore used have some serious disadvantages. On the onehand, there is a clear imbalance between the quantity of activesubstance required on or in the plant to achieve a positive effect andthe quantity of active substance actually applied by spraying ordusting.

On the other hand, the application of plant-protecting substances byspraying or dusting requires certain precautions to prevent damage tothe health of anyone present, which cannot always be adhered toparticularly in the case of houseplants and horticulture. The storage oflarge quantities of concentrated active substances constitutes anadditional hazard. Moreover, the user, particularly at a domestic orhorticultural level, generally finds it impossible to meter the activesubstance accurately onto the plant. This does not mean the preparationof a solution from a concentrate containing the active substance, butthe actual quantity of solution which is sprayed onto the plant. In mostcases too much or too little solution is sprayed on. Indoor spraying hasthe further disadvantage that the immediate area surrounding the plantwill also be sprayed with active substance, and consequently the plantsshould ideally be treated in the open. Any unused left-overs of solutionwhich have evaporated to a crust may cause problems if they cannot bedisposed of properly.

A further problem when spraying or dusting is the problem of drifting.In many cases it is undesirable that neighboring plants should come intocontact with the active substance. This is the case, for example, ifvegetables or fruits ready for harvesting are in the vicinity. It isparticularly undesirable for drifting to occur when using systemicallyacting herbicides, for instance those for combating quack grass.

A further disadvantage of previous methods of application is that afterthe plant protecting substances have been applied it is no longerreadily possible to tell which active substance has been used to treatthe plant.

OBJECTS OF THE INVENTION

It is an object of this invention to provide a device which improves theratio of active substance required to active substance applied in thefield of plant protection.

A further object is to provide a device which will increase safety whendealing with active substances in the field of plant protection.

Other objects and advantages of the invention will become apparent asthe description thereof proceeds.

DESCRIPTION OF THE INVENTION

The above objects are achieved according to the invention by means of adevice for the transcuticular application of systemic active substancesto plants in the form of an active substance carrier which stores theactive substance, one surface of the active substance carrier beingconstructed as a layer for coming into contact with the plant surface,through which the active substance is released onto the plant.

According to the invention, the device is brought into close contactwith the plant so that the active substance passes through the cuticleof the leaf or stalk into the plant and is there distributed throughoutthe plant by the plant metabolism.

In its simplest embodiment, the device according to the inventionconsists of a carrier which stores the active substance, as shownschematically in FIG. 1 of the attached drawings.

Suitable carrier materials are those which are capable of storing theactive substance in dissolved, suspended or solid form, such as paper,textile fibers, inorganic porous materials such as silicates orcarbonates, optionally mixed with binders, or poisoners. Paper andpolymers are the preferred carrier materials.

Furthermore, the active substance carrier comprises means for attachmentto the plant. These may be mechanical fasteners, for instance in theform of clips or bandages, or adhesive means, the adhesive fasteningmeans being preferred because of the ease of application. It isimportant that intimate contact is established between the part of theplant and the device so that the active substance passes into the plant.

In one particular embodiment, the underside of the carrier may comprisemicrofine fibers which penetrate into the outer layer of cells and thusimprove the uptake of active substance by the plant.

In another embodiment, the underside of the carrier, the side which willbe in contact with the plant, is coated with the active substance inmicrocrystalline form.

In another embodiment the upper side, that is, the side which will faceaway from the plant, of the active substance carrier is impregnated tomake it water repellent, which ensures that highly water-soluble activesubstances cannot be washed out. The impregnation may be effected, forexample, by spraying the carrier with suitable solutions known to thoseskilled in the art.

In a particular embodiment, the device according to the inventionconsists of a carrier with a self-stick polymer containing the activesubstance. Polymers of suitable composition and glass temperature forthis purpose are known to those skilled in the art. To improve thehandling of such a carrier it is advantageous if the upper side of thecarrier is coated with a non-stick material.

The embodiment of the device according to the invention is oflaminate-like construction.

As shown schematically in FIG. 2 of the attached drawings, the laminateddevice consists of a backing layer, a reservoir of active substanceconsisting of one or more layers, an adhesive layer and a removableprotective layer.

The backing layer, optionally impermeable to the active substance,closes off the structure of the laminates on the side which will faceaway from the plant. Suitable materials for forming the backing layerare polymers such as PVC, thin metal films, for instance of aluminum,optionally coated with a thin polymer film. If desired, the backinglayer may be colored so that the device is clearly visible on the plant.In another embodiment, the backing layer may be constructed, forinstance by means of a metal insert or textile insert, so that it actsas a support layer for stabilizing the laminate.

In a particular embodiment, the backing layer has a larger surface areathan the active substance reservoir arranged next to it and is coated onits underside with an adhesive material. In this way it simultaneouslyserves to fix the reservoir of active substance to the plant. Obviously,in this embodiment the separate adhesive layer shown in FIG. 2 is notrequired.

Adjoining the backing layer is the reservoir of active substance whichmay consist of one or more layers, although not all the layers needcontain active substance.

A multi-layer reservoir with layers of different active substancespermits storage of combinations of active substances. The layers maycontain agents which give slow release of the active substance. Inparticular, membrane-like layers are suitable for controlling therelease of active substance.

Materials which are suitable for forming the reservoir containing theactive substance are those which will store the active substance insolid, liquid or dissolved form and release it to the plant undercontrolled conditions.

The active substance may be embedded in the form of microcapsules in apolisher or may be present dispersed in a polymer matrix. It is alsopossible for the reservoir to form a cavity in which the activesubstance is contained, for example in liquid forth.

Suitable poisoners for forming the active substance carrier or thereservoir layer include, for example, polyvinyl alcohol, polyvinylacetate, plasticized polyvinyl chloride, plasticized polyamide, gelatin,waxes, polymers of monoesters of olefinic acids such as acrylic acid,methacrylic acid, polyhydroxyalkylacrylates or silicone rubbers.

Emulsion polymers such as PVC, polystyrene, polyvinyl acetates,polybutadiene, polyacrylonitrile, polyvinyl esters, polyvinyl ethers andcopolymers thereof are particularly preferred.

Emulsion-polymerized copolymers of methyl and/or ethyl esters of acrylicand methacrylic acid are especially preferred.

Fillers such as silica, for example, may be added to the polymers.

Adjoining the active substance reservoir is an adhesive layer.Self-stick polymers are well known to those skilled in the art. By asuitable choice of polymers the composition of the adhesive layer may bechosen so that it controls the rate of release of the active substancefrom the reservoir layer. Besides adhesive layers extending over theentire surface it is also possible to have adhesive surfaces using ringsor dots of adhesive. Adhesive surfaces extending over he entire areamust, in any case, be permeable to the active substance. This adhesivelayer may be omitted if the active substance reservoir consists of aself-stick polymer or the enlarged backing layer also has, on itsunderside, an adhesive layer which extends beyond the layer of activesubstance.

For protection, the reservoir of active substance has a removableprotective film adjoining the adhesive layer; alternatively, the entirereservoir of active substance may be sealed into a film which can betorn open. This arrangement is particularly recommended if the activesubstances involved are highly volatile.

In another embodiment, the device according to the invention is in theform of a sticker or label. The outside (back) of the device isconstructed so that it can be written on, for example, it is made of apaper-based material or a polymer film which can be written on.Important information such as the date of application to the plant,etc., can be written on the back.

It is also possible to print thereon important information such as thename of the active substance, storage dates or the duration of activityof the device from the date of application, during the actualmanufacture of the device. Other markings, such as color codes orgraphic symbols, may also readily be printed or stamped on.

These features provide, for the first time, a plant-protecting devicewhich will enable anyone to tell which active substance has been used onthe plant, even after the substance has been applied, without anyadditional tests being required.

The device according to the present invention is suitable fortranscuticular application of metered quantities of active substance toplants of all genera, particularly house and garden plants.

For this purpose, it is applied to the leaves or stems of the plants, sothat intimate contact is maintained between the plant and the device andthe active substance passes out of the reservoir and penetrates into theplant.

The transcuticular application of fungicidal and/or insecticidal activesubstances may be used to combat or ward off pests. The device of theinstant invention is particularly suitable for herbicidal treatment ofindividual plants. Suitable active substances in terms of the inventionare those compounds which have a fungicidal, herbicidal, insecticidaland/or acaricidal activity on the basis of their systemic effect.

The following tables list the preferred active substances which may beapplied, either singly or in combination, by means of the deviceaccording to the present invention.

    ______________________________________                                        SYSTEMIC active substances                                                    ______________________________________                                        1. with insecticidal, acaricidal and aphicidal activity                       Active substance                                                              Acephate                                                                      Aldicarb                                                                      Aldocycarb                                                                    Demeton                                                                       Demeton-S-m                                                                   Dicrotophos                                                                   Dimefox                                                                       Dimethoate                                                                    Formothion                                                                    Methamidophos                                                                 Methomyl                                                                      Mevinphos                                                                     Monocrotophos                                                                 Morphothion                                                                   Omethoate                                                                     Oxamyl                                                                        Oxydemetron-m.                                                                Phosphamidon                                                                  Prothoate                                                                     Thiometon                                                                     Vamidothion                                                                   2. with aphicidal activity                                                    Aphidan                                                                       Butocarboxim                                                                  Butoxycarboxim                                                                Heptenophos                                                                   3. Systemic fungicides                                                        Benomyl       Dodemorph    Nuarimol                                           Benodanil     Etaconazol   Oxycarboxin                                        Kitazin       Fenarimol    Prochloraz                                         Bitertanol    Fenpropimorph                                                                              Propiconazol                                       Carbendazim   Fosetyl      Triadimefon                                        Carboxin      Furalaxyl    Triadimenol                                        Cyprofuram    Imazalil     Tridemorph                                         Dichlobutrazol                                                                              Metalaxyl    Triforine                                          4. Herbicides                                                                 Acifluorfen   Chlortoluron Gibberellic acid                                   Alachlor      2,4-D        Glufosinate                                        Alloxydim     Dalaphon     Glyphosate                                         Bentazon      2,4-DB       Glyphosine                                         Bromoxynil    Dicamba      Ioxynil                                            Chlorfluorenol                                                                              Dichlorprop  MCPA                                               Chloridazon   Dichlofop    Mecoprop                                           Chlormequat   Diquat       Paraquat                                           Chloroacetic acid                                                                           Fluazifop    Pyridate                                           Chlorsulfuron Flurenol     Sulfometuron                                       ______________________________________                                    

The device according to the invention may contain the active substancein concentrations of between 10⁻⁶ and 200 mg, preferably 0.01-100 mg perdevice. The exact dosage depends on various parameters such as thenature of the polymer, the nature of the active substance carrier, theintended period of application, the thickness of the reservoir layer,and can be determined by simple experiments. Using the preciselypredetermined quantity of active substance in the device, it is possibleeven for non-experts to apply the required quantity of active substanceto achieve the desired effect without over- or under-dosing. This is notalways guaranteed by simply spraying or dusting.

The size of the area of contact of the device is not critical but shouldbe such that it does not extend beyond the parts of the plant, andnormally it ranges from 1 to 20 cm². The thickness of the device dependson the materials used, the layer structure, the quantity of activesubstance per unit area and the quantity of active substance which isintended to be delivered per unit time. It is generally between 5microns and 200 microns, preferably up to 100 microns, and can easily bedetermined by experiment.

Numerous advantages arise from using the device of the present inventionfor the transcuticular application of systemic active substances tocombat pests.

The active substances are fixed on the plant over a closely defined areain an outwardly "sealed" reservoir and not, as would be unavoidable whenspraying or dusting, uniformly distributed through the mediate vicinityof the plant. Accidental contact with the active substance is virtuallyeliminated. No protective precautions, such as breathing masks or thelike, are required when applying the substances. At the end of thetreatment any unused residues of active substance can be disposed ofrelatively easily by removing the reservoir of active substance anddiscarding it in the usual way. Useful insects, such as bees, are notendangered either during application of the active substance or duringthe period of treatment.

The active substance can be protected from external influences, such asUV radiation or washing away by rain, by being contained in the activesubstance reservoir. Consequently, preventive long-term treatment of theplants is substantially less problematic than with conventional methods.It is also easier to use sensitive active substances.

The quantity of active substance actually applied is drastically reducedcompared with that used for dusting or spraying. Accidental contact withthe active substance and even direct contact with the active substancelayer is not dangerous, compared with conventional preparations, becausethe active substance is relatively firmly fixed in the reservoir.

The device of the present invention may be produced, for example, by thefollowing methods. The active substance is dissolved or suspended,together with the polymer and any additives which may be used, in avolatile organic solvent, then poured out to produce a film ofpredetermined thickness and dried. The reservoir of active substancethus obtained can subsequently be provided with a backing layer, anadhesive layer and a protective coating and packaged.

If the carrier material consists of an absorbent material such as paper,the active substance reservoir can be produced by simply saturating theabsorbent material with a solution of the active substance; this may bedone, for example, by immersion or spraying.

The active substance may also be printed onto the carrier material usingknown printing methods, for instance on a polymer or preferably onpaper.

A carrier such as paper charged with active substance may be providedwith a backing layer which is sticky on the underside. After a removableprotective film has been applied, the resulting laminate is cut to therequired size.

In another embodiment, the active substance carrier is fixed to theplant by means of an adhesive tape cover.

Active substance reservoirs having a fine crystalline layer of activesubstance on their underside may be prepared by simply applying the finecrystalline active substance to a sticky carrier material.

TRIALS

A) Preparation of the Device According to the Invention

Composition of the active substance carrier layer

EXAMPLE 1

    ______________________________________                                        14.8 g Eudragit ® E 30 D (polymer)                                         5.2 g Dimethoate                                                             20.0 g Solid matter                                                           80.0 g Acetone                                                                100 g Solution                                                                ______________________________________                                    

The polymer is dissolved, together with the active substance, in acetoneand the solution is poured out to form a film on a carrier foil (12microns). After drying, the total thickness is about 100 microns.

EXAMPLE 2

Composition

    ______________________________________                                                  13.8 g Eudragit ® 30 D                                                    1.0 g Isopropyl myristate                                                     5.2 g Dimethoate                                                              20.0 g Solid matter                                                           80.0 g Acetone                                                               100.0 g Solution                                                     ______________________________________                                    

The method used is as described in Example 1; in this case the adhesivelayer is self-sticking.

B) Biological tests

1. Material and methods

1.1 Preparations

The devices (circular, about 5 cm²) are characterized as follows:

    ______________________________________                                              Dimethoate   Thickness of                                                                             Thickness of                                          Concentration                                                                              carrier foil                                                                             adhesive layer                                  Charge                                                                              mg/cm.sup.2  microns    microns                                         ______________________________________                                        1     approx. 2.5  12         approx. 80                                      2     approx. 0.5  12         approx. 40                                      3     approx. 0.5  12         approx. 80                                      ______________________________________                                    

1.2. Test method

The device is applied by simply pressing it: onto the top of the leaf inthe lowest leaf area; onto the underside of the leaf in the lowest leafarea; onto the stalk or petiole.

For the first test batch using Vicia plants a single reservoir wasapplied to each plant or leaf. In the second test batch on ornamentalplants, 1-4 reservoirs were applied per plant or petiole.

Infestation with Aphis fabae was then carried out after application bymeans of small dishes containing about 50 aphids, always on theuppermost leaf area, and accordingly on the other, untreated side of theleaf. Where the active substance had been applied to the stem,infestation was carried out on the top layer of leaves (see FIG. 3 ofthe attached drawings).

The results were evaluated by counting the number of dead and livingaphids (given as % mortality or activity) for Vicia after 1, 2 and insome cases 4 days. For the second test on ornamental plants, the resultswere evaluated 7 days after application.

2. Results

The test results from the first test on Vicia plants are shown inTable 1. These results show that dimethoate exhibits a translaminar anda systemic activity when applied by this method. The type of activitydepends on the dosage.

We also found that the highest activity rates are achieved when theactive substances are applied to the stem. The plant tolerance dependson the dosage and site of application, the latter being the criticalfactor. For example, at points where the dimethoate is rapidlytransported away, namely on the stem, no phytotoxicity is observed evenat the higher dosage.

                  TABLE 1                                                         ______________________________________                                        Activity (% A.) and tolerance (% Phyt.) of the device of the                  instance invention used against Aphis fabae after application                 to various sites and as a function of time                                             Evaluation after application/infestation                             Site of                        4th day                                        appli-     1st day     2nd day     %    %                                     Charge                                                                              cation   % A.    % Phyt.                                                                             % A.  % Phyt.                                                                             A.   Phyt.                           ______________________________________                                        1     Stem     82      0     100   0     100   0                              2              45      0     76    0     --   --                              3              35      0     54    0     --   --                              1     Top of   37      7     25    20    65   15                              2     leaf      5      0     11    0     --   --                              3               7      0     10    0     --   --                              1     Under-   20      3     33    15    39   25                              2     side      6      0      7    0     --   --                              3     of leaf   4      0      8    6     --   --                              ______________________________________                                    

Tests of Herbicidal Activity

1 mg of Glyphosate in a device according to the invention in the form ofa paper-based sticker, 3 cm².

Test Object

Quack grass in cotoneaster crops

Test method

One reservoir is attached to a leaf of each quack grass plant. After 3days the state of the plants is evaluated.

    ______________________________________                                                    % quack grass killed                                              ______________________________________                                        treated     100%                                                              untreated    0%                                                               ______________________________________                                    

There were no signs of phytotoxicity in the cotoneasters.

Effectiveness Against Spider Mites

Spider mites on potted hibiscus

Test Method

Sets of 2 hibiscus plants are placed side by side under differentspatial conditions. Natural attack by spider mites is awaited. Then eachplant is treated with 1 reservoir of 0.5 cm in diameter containing 10 mgof dimethoate. After 1 week and after 2 weeks the activity is evaluated(activity %)

    ______________________________________                                                       Application to                                                 Application to underside of Application to                                    stem           leaf         top of leaf                                       ______________________________________                                        untreated                                                                            --          0% (after 11/2 weeks the plants had                                           died off)                                                  treated                                                                       1st week                                                                             80          70           75                                            2nd week                                                                             100         90           92                                            ______________________________________                                    

While the present invention has been illustrated with the aid of certainspecific embodiments thereof, it will be readily apparent to othersskilled in the art that the invention is not limited to these particularembodiments, and that various changes and modifications may be madewithout departing from the spirit of the invention or the scope of theappended claims.

We claim:
 1. A device for transcuticular administration to a plant of asubstance systemically active in the plant, the device being in the formof a laminate including a systemically active substance to be releasedto the plant in metered quantities, said laminate comprising in order:(1) a backing layer impervious to the active substance, (2) an internalactive substance reservoir layer formed of a carrier matrix in the formof a polymeric or absorbent material layer having incorporated thereinsaid active substance, and (3) an outer adhesive layer adherable to theplant and permeable to the active substance, said laminate being adheredto said plant through contact with said adhesive layer, and releasingsaid active substance in metered quantities from said reservoir layerthrough said adhesive layer to said plant.
 2. A device fortranscuticular administration to a plant of a substance systemicallyactive in the plant which comprises a device in the form of a laminateincluding a systemically active substance to be released to the plant inmetered quantities, said laminate comprising in order:(1) a backinglayer impervious to the active substance, (2) an adhesive layercoextensive with said backing layer and (3) an external active substancereservoir layer formed of a carrier matrix in the form of a polymeric orabsorbent material layer having incorporated therein said activesubstance, and wherein said reservoir layer is coextensive with only aportion of said adhesive layer which device is adherable to said plantthrough the portion of said adhesive layer not coextensive with saidreservoir layer to bring said reservoir layer in contact with saidplant, which will release said active substance in metered quantitiesthrough said reservoir layer directly to said plant.